Titanium furnace or the like



April 24, 1956 E. w. JOHNSON TITANIUM FURNACE OR THE LIKE Filed Jan. 5, 1955 United States Patent O )aan 2,743,307 v TITANIUM FURNACE OR THE LIKE Edwin W. Johnson, Pittsburglnla., assigner to Westinghouse Electric Corporation, East Pittsburgh, Pa., n corporation of Pennsylvania Application January S, 1955, Serial No. 479,881 Claims. (Cl. 13-31) My invention relates to various practical improvementsr inthe structural design of electric arc furnaces for :the melting and casting of titanium, zirconium, molybdenum and` other refractory chemically active metals and their alloys. rPhe melting of such metals is -usually conducted in an inert gas, in `a watercooled copper vessel or mold, as a gaseous pressure which is frequently of the order of a lifth of an atmosphere, but which may range from a high vacuum to pressures whichare above atmospheric pressure. The necessary heat is supplied by one or more electric arcs which are propagated between the molten ybath and one or several electrodes positioned above it. My invention was particularly designed for ya furnace using Vconsumable electrodes, made of the metal which is being melted, termed the furnace-charge. Many of the elements of my furnace, however, can be advantageously used in furnaces incorporating nonconsumable electrodes of a refractory conductor, `such as tungsten or carbon, in which case the metal to be melted is supplied to the bath in granular form alongside of the electrode. My design is intended primarily for. use with titanium and its alloys, but the designis applicable also to the melting and casting of many other materials, such as zirconium, hafnium, molybdenum, vanadium, nickel, cobalt and iron, as well as their alloys. Because of the necessity that the furnace shall bevacuum-.tighn or substantially so, it is sometimes called a vacuum Iarc. furnace.

The novel features of my furnace include a readily removable mold or liner which is relatively free to expand both longitudinally and radially, and which can be readily removed so that it can be reconditionedor replacedV after each five to ten melting-cycles, more or less; a mold having a detachable bottom which is tted with a smalldiameter stud which isscrewed into the mold-bottom and melted into the ingot, so that the ingot is mechanically and electrically connected to the bottom, and canV be forcibly pulled down after the melting and casting operation, in case there should be any sticking ofthe ingot in the side walls of the mold; and an enlarged head-section which is disposed around a hole in the lloor or other supporting structure, being preferably grounded to said floor or supporting structure, 4in combination with a depending removable water-jacketed mold structure which is in.- sulatedly carried by said enlarged head structure, and an upwardly extending removable electrode-housing portion which is insulatedly and removably carried by the. top of the head-portion and which completes the evacuated chamber. The various advantages and operations of these various parts, and other novel features, will be described hereinafter in greater detail;

An exemplary form of embodiment4 of my invention is shown in the accompanying drawing, wherein Figure 1 is a somewhat diagrammatic central vertical sectional view of a preferred or illustrative form of embodiment of my furnace assembly, approximately on the section-plane indicated at l-l in Fig;

Fig. 2 is a sectional plan-view, approximately on the planendicated at Il-H in rFig;l l, and

Fig. 3 is a vertical central section-a1 view `of the waterjacketed mold liner, which constitutes the side walls of the mold or Crucible, on a slightly larger scale than is shown in Fig. 1.

My furnace is illustrated as being mounted on a platform 1 which may be either a floor or the top of a supporting frame or structure, having therein a hole 2, around which an enlarged head-section 3 of my furnace structure is disposed. In the illustrated furnace, this head-section 3 consists of a welded large-diameter stainless-steel tank having a centrally perforated bottom-plate 4', which rests on the platform 1, and a ring-shaped top plate 5, which is a plate having a rather large central perforation therein, almost as large as the inner diameter of ,the head-section 3.

From the bottom plate 4 of the head-section 3, there depends the mold assembly 6 of my furnace. It is secured to the bottom plate 4' by some insulated bolts 6', and it is insulated therefrom by a suitable insulating ring 6"'. In the normal operation of my furnace, these bolts 6 are never removed, except -to repair the mold assembly 6.

The mold assembly 6, in the illustrated embodiment, includes a corrosion-resistant, nonmagnetic water-jacket 7, which may be made of stainless steel or. brass, within which is removably mounted a.V tubular copper liner 8, which is sometimes referred to as the mold body, or as the side walls of the mold or Crucible. The mold assembly 6 also includes a removable water-cooled mold-bottom` 9. In the illustrated design, the water-jacket 7 ofy the mold has integral or permanently connected top and bottom flanges 11 and 12, respectively. l

The mold liner 8 is `a straight copper tube which is removably fitted within separate ring-shaped or centrallyr bored top and bottom retaining plates 13'and 14- of the water-jacket 7, these retaining plates being held watertight against the top and bottom ilanges 11 and 12, respectively, by suitable means `such as O-rings 13 rand-14'. It is an important 4feature of my invention that the tubular mold liner 8 is quickly removable from the top and bottom retaining plates 13 and 14, while at the same time maintaining the necessary Valentini-tightness of the furnace-structure, and providing for necessary expansions and contractions. To this end, the top and bottom ends of the liner 8 are sealed within the bores of. the top and bottom retaining plates 13 and 14, by means of O-rings 13 and 14". The top retaining plate 13 and the top flange 11 are bolted together by the insulated bolts 6 which connect the mold assembly 6y to the bottom plate 4 and the insulating ring 6V of the head sectionV 3; The bottom flange 12 and the bottoni retaining plate 14 are held together by machine screws 15.

The mold-bottom 9 consists of a raised copper portion 16 which slidably lits within the bottom of the mold.' liner 8. This raised copper portion 16 is attached to a ilangelike base-plate 17, which fits removably up against the 'bottom retaining plate 14, being kept vacuum-tight by anr interposed O-ring 17. Underneath this flange-like base-plate 17, there is disposed a bottom enclosure-plate 18, which may lit removably up against the flange-likel base-plate 17, being keptwvater-'tight by an interposed O-ring 18. Provision is made for water-coolingthe moldbottom 9, as indicated at 19. The entire bottom-flange assembly, from the bottom flange 12 to the bottomV enclosure-plate 18, is removably held in place 'oy quickly disengageable bolts 15.

While removable water-cooled mold-bottoms have been used before, in vacuum-type electric-arc furnaces, I have introduced a novel feature which I consider to be a worth-while improvement. l make my raised copper portionv 16 thick enough so that its top may be provided with a relatively small-diameter tapped central hole' 20,

melting furnance, so far as I am aware.

, 3 for receiving a threaded small-diameter starting-stud 20' which is made of the same material as the furnacecharge. The lower end of the stud 2b is threaded into the hole 2li in the raised portion lo of the mold-bottom 9. Since the mold-bottom is water-cooled, this hole-htting bottom end of the stud Ztl does not melt during the operation of the furnace.y However7 the upper end of the stud melts into the ingot and forms a constituent part of the ingot during the initial stages of a melting and casting operation of the furnace. This small startingstud 20 performs several useful purposes, as will be described hereinafter during the description of the operation of the apparatus.

The ring-shaped top plate 5 of the enlarged head-section 3 supports a tall upstanding smaller diameter electrodehousing 2l, which completes the vacuum-tight envelope of the furnace. This electrode-housing, in the illustrated form, is a'brass structure, consisting essentially of a tall vertical tube 21', the lower end of which is securely and hermetically attached within the perforation of a bottom ange or plate 22, while the top end of the tube 21 is securely and hermetically attached to a flange 23. The lower portion of the electrode-housing tube 21', and the lower flange or plate 22 of this electrode housing are preferably cooled, as by water flowing through copper tubing 24. The bottom dange or plate 22 of the electrode-housing 21 is nsulatedly mounted on the ring-shaped top plate 5 of the enlarged head-section 3, by means of a' thick insulating ring or washer 25, these 'parts being removably held together by means of some removable insulated bolts 26. Vacuum-tightness is mantained by suitable O-rings 22' and S', disposed above and below the insulating ring 25, so that the vacuum-tightness is assured when the bolts 26 are tightened in place.

The top flange or plate 23 of the electrode-housing 2l is provided with a slide-seal member 2'7, which makes a Vsubstantially vacuum-tight slide-seal tit with a long vertically-disposed tube 28 which extends into the furnace-chamber and serves as an electrode-holder, for supporting a consumable electrode 29 within the furnace. lt is necessary or desirable to water-cool the electrode-holder 28, as by means of an inlet pipe or hose 31, and an outlet pipe 32.

The lower end of the electrode-holder 28 must be designed to mechanically support the weight of the consumable electrode 29, while at the same time it conducts the necessary heavy current into the electrode, and it provides a means for quick detachment of the parts. In my present invention, I believe that l have introduced an innovation, in the form of a turnbuckle, which is shown as a small adapter 33 which threadedly engages the outside of the lower end of the electrode-holder 28, and which also threadedly engages an upwardly extending plug 34 of a nonconsumable electrode-top or head 35, which may conveniently consist of a short length of wrought bar of the same material as the consumable electrode 29, which may be titanium or a titanium alloy, or other like material such as has been mentioned. Preferably, the top of the consumable electrode 29 is welded to the bottom ofthe non-consuming electrode-head 35, as shown at 36, before the turnbuckle 33 .is brought into place. The turnbuckle can then be turned to tightly secure the electrode-head 3S to the bottom of the electrode-holder 2li, without requiring the rotation of either the electrode or the electrode-holder, which is a very great advantage, not realized in any previous consumable-electrode arc- The electrode 29, with its electrode-head 35, is secured in anydesired rotational orientation by tightening a lock-nut 37 which is situated above the turnbuckle or adapter block 33.

When i use a consuming electrode 29 as shown, and possibly sometimes also when a nonconsuming electrode is used, I prefer to make the electrode the negative terminal of a direct-current source of energy, as indicated at which is connected to the top of they electrode-holder 28. The mold-bottom assembly 9 is then connected to the positive terminal (-1-) of the source. While this is my preferred form of energy or excitation for the melting arc, it will be understood that the directcurrent polarities could possible be reversed, or that an alternating-current are-sourcey might also be used, with proper precautions as to the relative temperatures of the electrode and the melt, particularly if a nonconsuming electrode is used.

My enlarged head-section 3 performs many novel and useful functions. The outer portion of its perforated bottom plate 4 serves as a mounting-ange for sustaining the lentire weight of the furnace. The inner portion of this perforated bottom plate d, inside of the furnace, serves as a wide ledge which is situated at a level directly above the upper extremity of the mold S, and having unimpede-d communication for the passage of volatile condensable material which is given off by the melt. This volatile condensablematerial usually consists mainly of a small quantity of magnesium chloride which, with other impurities, is commonly present in the titanium sponge of: which the electrode 2.9 is commonly made. These impurities often cause didicuities in the control of the arc, and they should be prevented, to the greatest extent possible, from re-entering the molten bath. The horizontal seat or ledge which is formed by the upper surface of my main support-plate 4 of the enlarged headsection 3 is large enough to retain or hold a significant amount of such volatile impurities, after they have condensed in the enlarged head-section 3. This novel construction also avoids, or vastly retards, the cumulative deposition of the condensable materialen the upper portions of the side walls of the mold 8.

My enlarged head-section 3 also provides a means for the mounting of an arc-viewing port 38, and/or an eX- plosion disc 39, both of which, when used, should be in line-of-sight relation to the arc at the bottom of the consumable electrode 29.' The view-port 3S and the explosion or rupture-disc 39 are carried by the bottom flange 22 of the electrode-housing 21, which is supported on the top of my enlarged head-section 3. The electrode 29 and the housing-tube 21 are smaller in diameter than the copper mold 8. Hence the top of the melt, below the bottom of the electrode, can be viewed through the viewing-port 38.

My enlarged head-section 3 is at ground potential, whereas the electrodehousing 21 and the mold assembly 6 are at the opposite electric potentials of the arc which plays between the bottom of the electrode 29 and the top of the melt which is contained in the mold assembly 6. Thus, I use a grounded head-section 3 having an insulating ring 6 underneath the saine, and a second insulating ring 2S above the same, thus providing a double insulation between the electrode potential and the ingot potential. This double insulation is quite useful in a device which is subject to as much spattering as is a vacuum-type titanium furnace.

My enlarged head-section 3 is also useful in providing a convenient mounting-space for a plurality of ngers or electrode-guides 41 which have bent top ends which are insulatedly secured to the bottom of the bottom flange 22 of the electrode housing 2l. If my head-section were not of a rather considerably larger diameter than the electrode 29, there would not be room for this sort of construction. As it is, the bent top ends of the lingers 41 are insulated from the electrode-housing fiange 2?, by means of a thickness of insulation 42. The electrodeguiding lingers 42 are quite important, if not absolutely necessary, in keeping the electrode 29 centered in the mold 8.

vThe peripheral side-walls of my enlarged head-section 3 also afford a convenient place for the attachment of various service-ports for the furnace. Thus, at this point, there is provided a pumping connection 43, whereby the enclosure may be evacuated, as by means of diagramniaticallyl indicatedA diffusion andV mechanical pumps 43'. Als,0 connected tothe sidev walls of thev enlargedV head section 3, I have shown av small pipe 44; which is con* nected to aA compressed-helium tank 45 through avalve 46 sothat, after a suitable vacuum has been attained byfmeans of the pumping mechanism 43, an inert atmosphere such asv helium, argon or a mixture of these gasiS, may be introduced through thesmall pipe or port 4.4'. The pressure of the inert gasrin the furnaceis readily adjustable by means of. the pumping mechanism.

My complete furnace-assembly includes several auxiliary components. Inthe illustrated form of embodiment, IV show two spaced. upstanding vertical pipes 51 and.. 52,v which are spaced. apart, andA held, at their top, by a.crosspiece.53. In-the-particular formof embodiment which is illustrated, these two vertical pipes 51 and 52 serves. asguide-rails or columns, for guiding two separate vertically movingearriages 54 and 55. The topmost carriage..54.has artoftset partA 54' which insulatedly supports the top of the electrode-holder 28 in a position which is laterally oisetwith respect to the plane of the two vertical guide-pipes 51 and 52, while thelowermost carriage 55 has laterally olset insulated arms 55 andy 55. which are attached to the electrode-housing tube 21.

I have shown a preferred form of structure for the vertically moving carriages 54 and 55. The lower carriage 55 is shown in horizontal' section in Fig. 2, as well as being shown in vertical section in Fig. l, and this carriage willV be described more in detail. Since the two carriages are essentially similar, the same description will apply for the upper carriage 54L The vertically sliding carriage 55` is shown as being mountedon the two. guide-columns-Sl and 52` by means of two long sleeves or pipes 61v and 62, which encircle the supporting columns, and which are provided, at their upperA and lowerr ends, withA bushings 63 for facilitating the sliding motion over the vertical columns 51 and 52. Each of` these elongated' sleeves or pipes 61 and 62 is provided with a laterally extending flange or lug 61 and 62', respectively, and these lugs are joined by a stiff in sulatingplate 64. `The laterally extending arms 55 and 55"A are carried by the insulating. plate 64;

Suitable lifting mechanisms are provided, for independently lifting orV lowering. the respective carriages 54 and 55', as is diagrammatically indicated by the arrows 54L and- 55L, respectively. The means for powering and controlling these lifting and lowering mechanisms are not a part of my present invention, other than the fact that suitable mechanisms shall be provided. As shown, the lifting-mechanisms 54L andV 65 which are attachedy to the 64of`the twoV carriages.

In the operationl of the furnace, the mold-bottom 9 isy lirst removedy for the insertion of the small-diameter threaded: starting-stud 2,0', after which, the mold-bottom 9 is replaced and bolted in its normal position at the bottom of the mold liner 8, as shown in Fig. 1. Then the electrode-housing 21 is unfastened from the top of the enlarged'head-section 3, by loosening the removable bolts 26, and both of the vertically movable carriages 54 and 55are` raised straight upwardly, to near their upper limits of travel. In this position of the parts, the bottom 22 of the electrode-housing 21 will have been lifted straight up, away from the topv of the enlarged head-section 3, to a level which is slightly above the protruding lower end of the electrode-holder 28, so that the turnbuckle adapter 33 is accessible below the lower end of electrodeguides 41j.

A new furnace-charge is now prepared, outside of the furnace, by welding the top end of a new consumable electrodeY 29 to the bottom of the electrode-top 35. The bottom of the new electrode 29 is then lowered into the enlarged opening at the top of my enlarged head-section 3. Here, again, a further advantage of the enlargement of the headlsection 3 will be perceived, because it provides respective insulating plates 551. are' attached to blocks t;

room for the insertion of the electrodeV 29'A from the top', while keeping the electrode in a position which is: tilted only very slightly out of the verticalv position, which is quite an advantage in handling the fragile electrode. The tilting out of the vertical position need beV onlyy slight-in order that the top part of the electrode may be disposed to one side of the elevated electrode-housingZl, until the electrode 29 is lowered far enough so that its top. end or head 35 is below the lowermost end of the depending electrode-guiding lingers 41 which are carried by the: bottom of the electrode-housing; 21. After this, the electrode 29 may be brought into a fully verticallposition,andthe turnbuckle adapter 33 may then be applied, and locked in position, to securely attach the electrode-top 35y to thev bottom of the'electrodeholder 28.

After the turnbuckle 33 has been tightenedy in place, the lower lifting-carriage 55 may now be lowered until the bottom flange 22 of the electrode-housing: 21 is lowered onto the upper insulating ring 25 of, the headsection 3, after which the bolts. 26 may be reapplied or tightened, and the furnace is then ready to be'evacuated.

After evacuation, and the insertion of a suitable inert gas such as helium, the pressure of the inertv gas in the furnace is adjusted to the desired degree of vacuumor pressure, the cooling water is then turned on, in the various cooling-jackets, and the mainv arc-power supply is applied, so that the open-circuit arc-voltage is applied across the electrode 29 and the starting stud 20.

The arc is initiated by manipulating the liftingmechanism 54L of the upper carriage 54,v so as to lower' the clectrode-holder 28, with its depending electrode 29, until the bottom end of the electrode touches the starting-stud 2G'. A heavyv momentary flow of shortfcircuit arc-cur.` rent thereupon flows through the stud; This quickly melts the contacted portion ofv the stud, initiating the arc, and the arc-heat quickly melts the remainder. of the emergent portion of the stud, andl starts toA melt` the end of the electrode. This results in` the quick formation of a layer of molten metal over the raised portion 16 of the mold-bottom 9, thus protecting'the mold bottom from the direct impingement of the arc, preventing the arc from approaching the mold-bottom closely enough todamage: it.

It is only necessary that the threaded lowermost end of the stud 20 shall be of a small diameter, relativel to the inner diameter' of the moldvliner 8. This isnecessary in order that the threaded'lowermost end of the stud may be threaded into the threaded hole 20 in the top of the mold-bottom 9; The top of the stud 20 may be enlarged, if desired, or itV may be somewhat pointed at its top, as indicated in Fig. l, to limit the initial contact-area with the electrode, so as to promote a quick melting away of the top end of the stud, so as'to minimize the. possibility of its becoming welded to the electrode during the initial starting of the furnace.

During the operation of the' furnace, the molten pool is heated directly by the arc, as well as by thevirtually continuous supply of moltenv charge. As the melting progresses, the electrode; 29 is fedl downwardly, by permitting the upper carriage'54 to drop slowly at whatever rate may be necessary to maintain the desired arc-length. This may be accomplished by manual manipulation or by automatic feeding-apparatus (not shown) which forms no part of my present invention, other than thefact that the electrode 29 must be lowered at a rate suitable for keeping the lowermost end of the electrode spaced by a suitable arc-length from the molten topV of the ingot, as the ingot builds up in the mold-liner 8;

The device is arranged so that, when the electrodeholder 28 has been lowered to a predetermined limiting position, the consumable electrode 29, which constitutes the furnace-charge, will have all have been melted away, substantially precisely upto the line of welding 36 which connects the top of the electrode 29 to the bottom of the electrode-top 35. The arc-power supply is then turned otr', and the ingot in the moldisfallowed to cool until its 7 surface-temperature is below visible red heat. This cooling period can be hastened if the partially evacuated envelope of the furnace is filled with helium at atmospheric or a higher pressure, during the cooling.

After the ingot has sufficient cooled, the mold-bottom 9 is first engaged by a suitable lift-support 70, after which the furnace is opened by discngaging the bolts l5 which hold the removable mold-bottom 9-in place. The moldbottom 9 is then lowered, by lowering its support '76, until the ingot has been entirely removed out of the bottom of the mold-liner 8. During this operation, the screwthreaded connection between the stud 20 and the moldbottom 9 may sometimes be valuable in making possible the application 0f additional downward pressure on the mold-bottom, to overcome an occasional sticking of the ingot in the mold-liner 8.

The cooling water may be turned ofi, usually after the ingot has been lowered out of the mold 8.

The furnace is then opened at the junction between the bottom of the electrode-housing 2i and the top of the enlarged head-section 3, by disengaging the bolts 26. The electrode-holder 28 and the electrode-housing 2l are then raised to near their upper limits of travel. The inside sorfaces of the electrode-housing 21', the head-section 3, and

the mold-liner 8, andthe exposed surfaces of the lower end l of the electrode holder 23 can now be cleaned of all lspattered and condensed matter which may have accumulated during the melting operation. Such a cleaning is necessary after each melting operation, irrespective of the nature or composition of the furnace-charge, and it is greatly facilitated by having the mold-bottom 9 removed downwardly, and by having electrode-housing 21 raised straight up, well clear of the enlarged head-section 3, as in my present design.

To remove the ingot from the mold-bottom 9, the ingot is simply unscrewed, thereby removing the downwardly projecting part of the stud 20 (which is now an integral part of the ingot) from the threaded hole 20 in the moldbottom 9.

The unconsumed top-member 35 of the same material as the ingot is now removed from the bottom of the electrode-holder 28, by unscrewing the turnbuckle adapter 33, and the furnace is then ready for a repetition of the melting cycle.

As has been discovered in other furnaces, it is desirable that at least the interior surface of the copper mold-liner 8 should be chromium-plated in order to increase the melting-rate by its reiiecting properties, as well as to substantially reduce the rate of erosion of the mold-liner 8, thus prolonging its life.

While I have illustrated my invention in but a single illustrative form of embodiment, I wish it to be understood that I am not limited to this precise form of structure, as I contemplate that various changes may be made, within the spirit of the invention, in the way of the substitution of equivalent devices, or by the addition or omission of certain parts, or by the application of the essential features of the furnace to other uses and applications, other than in connection with the precise methods and processes herein described.

I claim as my invention:

l. A furnace for melting and casting metal, comprising a substantially hermetically sealed enclosure including a removable metal mold liner having at least an open top end, a cooling-liquid jacket surrounding said mold liner, and sealing rings for sealing the respective ends of said mold liner to the respective ends of said jacket in a manner such as to maintain the substantially hermetic sealing of the enclosure and the substantially liquid-tight quality of the jacket, said sealing rings including at least one sealing ring between the outer surface of said mold liner and a Ybore at one end of the jacket, saidsealing rings further including at least one sealing ring between a transverse surface of the mold liner and a transverse surface of the jacket at one end of the mold liner.

2. A furnace for melting and casting metal, comprising a substantially hermetically sealed enclosure including an enlarged intermediate supported section, a removable depending cooling-liquid jacket depending from said intermediate section, a removable cylindrical metal mold liner disposed within said jacket, said mold liner having open top and bottom ends, and a removable liquid-cooled metal mold-bottom having a raised central portion disposed within the bottom end of said'mold liner; said jacket having a side-wall portion and laterally extending top and bottom flanges, and a separate centrally bored retaining plate dirsposed at at least one end of the jacket on the outside of the flange at that end, with a sealing ring disposed in between; sealing rings disposed between the respective ends of the rnold liner and the bore of the jacket; said moldbottorn having a laterally extending base-plate disposed below said bottom retaining plate, with a sealing ring disposed in between; and a disengageable clamping means for clamping said base-plate to the bottom ange of the jacket.

3. An electric-arc furnace for melting and casting metal, comprising a substantially hermetically sealed enclosure including a liquid-cooled metal mold at its bottom, and an electrode extending downwardly into the mold, said mold having open top andbottom ends, a removable liquidcooled metal mold-bottom disposed within the bottom end of the mold, the top of said mold-bottom having a relatively small-diameter tapped hole therein, a stud of substantially the same material as said cast metal, screwed into said tapped hole, and a means for controlling the vertical distance between the mold-bottom and the bottom of the electrode.

4. An electric-arc furnace for melting and casting metal, comprising a substantially hermetically sealed enclosure including a liquid-cooled metal mold at its bottom, an enlarged head-section disposed immediately above the top of the mold and having substantially unimpeded communication for the passage of volatile condensable material from said mold, an upstanding electrode-housing disposed above said enlarged head-section, a substantially hermetically tight slide-seal at the top of said electrodehousing, and an electrode-assembly comprising a vertically Vmovable electrode-holding portion extending through said slide-seal, the outside portion of said electrode-holding portion including a means whereby the same may be suspended, and an electrode portion at the bottom of said electrode-holder, said electrode portion extending downwardly into said mold and being of a substantially smaller diameter than said mold, whereby the bottom of said enlarged head-section provides a ledge which is large enough to contain a significant amount of such condensed material during the operation of the furnace, whereby to substantially prevent the dropping of the condensed material into the arcin g area, and to substantially prevent the cumulative deposition of the condensed material on the upper portions of the side walls of the mold.

y5. An electric-arc furnace for melting and casting metal, comprising a substantially hermetically sealed enclosure including a liquid-cooled metal mold at its bottom, an enlarged head-section disposed immediately above the top of the mold, a smaller-diameter upstanding electrodehousing including a bottom ange-plate disposed immediately above the enlarged head-section, a substantially hermetically tight slide-seal at the top of said electrodehousing, a vertically movable electrode-holder extending through said slide-seal, a consumable electrode ofthe metal which is to be melted, secured to and depending from said electrode-holder, and an electrode-guiding means, secured to and depending from the bottom flange-plate of said electrode-housing, and disposed within said enlarged headsection, for guiding said electrode.

6. An electric-arc furnace for inciting and casting ifs-tab comprising a substantially' hermeticaliy sealed enclosure including a iiquid-cooled metal mold at its bottom, an enlarged head-section disposed immediately above the top of the mold, a smaller-diameter upstanding electrode-housing including a bottom ange-plate disposed immediately above the enlarged head-section, a substantially hermetically tight slide-seal at the top of said electrode-housing, a vertically movable electrodeholder extending through said slide-seal, a consumable electrode of the metal which is to be melted, secured to and depending from said electrode-holder, and one or more ports in the bottom flange-plate of said electrodehousing, in line-of-sight relation to the region surrounding the bottom of said electrode.

7. An electric-arc furnace for melting and casting metal, comprising a substantially hermetically sealed enclosure including a liquid-cooled metal mold at its bottom, an enlarged head-section disposed immediately above the top of the mold, a smaller-diameter upstanding electrode-housing including a bottom tiange-plate disposed immediately above the enlarged head-section, a substantially hermetically tight slide-seal at rthe top of said elec trede-housing, a vertically movable electrode-holder extending through said slide-seal, a consumable electrode of the metal which is to be melted, and a coupling means including a turnbuckle-adapter for connecting the top of the electrode to the bottom of the electrode-holder.

8. An electric-arc furnace for melting and casting metal, comprising a substantially hermetically sealed enclosure including a liquid-cooled metal mold at its bottom, an enlarged head-section disposed immediately above the top of the mold, a smaller-diameter upstanding electrodehousing including a bottom flange-plate disposed immediately above the enlarged head-section, a substantially hermetically tight slide-seal at the top of said electrodehousing, a vertically movable electrode-holder extending through said slide-seal, a consumable electrode of the metal which is to be melted, a coupling means including a turnbuckle-adapter for connecting the top of the electrode to the bottom of the electrode-holder, and an electrode-guiding means, secured to and depending from the bottom ange-plate of said electrode-housing, and disposed within said enlarged head-section, for guiding said electrode.

9. An electric-arc furnace for melting and casting metal, comprising a substantially hermetically sealed enclosure including a liquid-cooled metal mold at its bottom, an enlarged head-section secured to the top of the mold, a smaller-diameter upstanding electrode-housing including a bottom flange-plate detachably secured to the top of the enlarged head-section, a substantially hermetically tight slide-seal at the top of said electrode-housing, a vertically movable electrode-holder extending through said slide-seal, a consumable electrode of the metal which is to be melted, a coupling means for removably securing the top of said electrode to the bottom of said electrodeholder, a lifting-means for raising and lowering said electrode-holder in a substantially straight up-and-down direction, and a liftingmeans for raising and lowering said electrode-housing in a substantially straight up-and-down direction after its bottom flange-plate has been disengaged from the top of the enlarged head-section, the extent of the vertical raising of said electrode-housing being at least sufficient to permit a new electrode to be lowered, in an only slightly olf-vertical position, through the opened top of the head-section and into the mold, and then to permit the coupling means to be manipulated to secure the top of the electrode to the bottom of the electrode-holder.

10. An electric-arc furnace for melting and casting metal, comprising a substantially hermetically sealed enclosure including an enlarged intermediate supported section, a smaller-diameter depending liquid-cooled depending metal mold liner having its upper end secured to the bottom of the intermediate section, said mold liner having open top and bottom ends, a removable liquidcooled metal mold-bottom disposed within the mold liner, a means for removably supporting the mold-bottom within the mold liner, a smaller-diameter upstanding metal electrode-housing including a bottom ange-plate removably secured to the top of the enlarged intermediate section, a substantially hermetically tight slide-seal at the top of said electrode-housing, a vertically movable electrode-holder extending through said slide-seal, a consumable electrode of the metal which is to be melted, a coupling means for removably securing the top of said electrode to the bottom of said electrode-holder, a liftingmeans for raising and lowering said electrode-holder in a substantially straight up-and-down direction, and a lifting-means for raising and lowering said electrodehousing in a substantially straight up-and-down direction after its bottom flange-plate has been disengaged from the top of the enlarged intermediate section, the extent of the vertical raising of said electrode-housing being at least suilicient to permit a new electrode to be lowered, in an only slightly ott-vertical position, through the opened top of the intermediate section and into the mold liner, and then to permit the coupling means to be manipulated to secure the top of the electrode to the bottom of the electrode-holder.

References Cited in the le of this patent UNITED STATES PATENTS 1,671,461 Bagley May 29, 1928 2,541,764 Herres et al Feb. 13, 1951 2,640,860 Herres June 2, 1953 2,662,104 Southern Dec. 8, 1953 2,697,126 Herres Dec. 14, 1954 OTHER REFERENCES Metals Technology, vol. 13, September 1946, Technical Publication #2052, Parke and Ham, 12 pp. 

1. A FURNACE FOR MELTING AND CASTING METAL, COMPRISING A SUBSTANTIALLY HERMETICALLY SEALED ENCLOSURE INCLUDING A REMOVABLE METAL MOLD LINER HAVING AT LEAST AN OPEN TOP END, A COOLING-LIQUID JACKET SURROUNDING SAID MOLD LINER, AND SEALING RINGS FOR SEALING THE RESPECTIVE ENDS OF SAID MOLD LINER TO THE RESPECTIVE ENDS OF SAID JACKET IN A MANNER SUCH AS TO MAINTAIN THE SUBSTANTIALLY HERMETIC SEALING OF THE ENCLOSURE AND THE SUBSTANTIALLY LIQUID-TIGHT QUALITY OF THE JACKET, SAID SEALING RINGS INCLUDING AT LEAST ONE SEALING RING BETWEEN THE OUTER SURFACE OF SAID MOLD LINER AND A BORE AT ONE END OF THE JACKET, SAID SEALING RINGS FURTHER INCLUDING AT LEAST ONE SEALING RING BETWEEN A TRANSVERSE SURFACE OF THE MOLD LINER AND A TRANSVERSE SURFACE OF THE JACKET AT ONE END OF THE MOLD LINES. 